Optoelectronic devices are widely used in optical communication systems, where electrical signals containing information to be transmitted are modulated on corresponding optical signals. The optical signals are propagated between the optoelectronic devices through optical propagation channels (for example, optical fibers).
A typical optoelectronic device comprises a chip of semiconductor material with optical circuits integrated, hereinafter OIC (“Optical Integrated Circuit”) chip, for modulating/de-modulating the electrical/optical signals into the corresponding optical/electrical signals, respectively, a chip of semiconductor material where electronic circuits are integrated, hereinafter EIC (“Electronic Integrated Circuit”) chip, for processing the electrical signals according to the specific functionality of the optoelectronic device, and optical components for transferring the optical signals to/from the OIC chip. The OIC chip generally comprises waveguides for propagating the optical signals among the optical circuits integrated therein, exposed regions (exposed on surfaces of the OIC chip) for sending/receiving the optical signals, and optical gratings for transferring the optical signals between the waveguides and the exposed regions. A typical OIC chip comprises longitudinal waveguides, where optical signal propagation takes place only along a longitudinal direction (i.e., parallel to a substrate of semiconductor material from which the OIC chip is formed). This may involve coupling difficulties between the OIC chip and the optical propagation channels.
Indeed, in the case of exposed regions being made on an upper surface of the OIC chip (so as to send/receive the optical signals along a transverse direction, perpendicular to the longitudinal direction), a vertical coupling between the optical propagation channel and the OIC chip may be needed. However, the vertical coupling may need structures for supporting the optical propagation channel, with a consequent increase of space occupation by the optoelectronic device. Moreover, in many implementations, the optical propagation channel is subject to non-negligible curvatures to achieve the vertical coupling. This may cause damage of the optical propagation channel, and/or propagation errors of the optical signals through it. Instead, in the case of exposed regions made on a side surface of the OIC chip (so as to send/receive the optical signals along the longitudinal direction), the production process of the OIC chip needs additional operations (for example, side surface lapping), and therefore an increase of the optoelectronic device costs.
For example, U.S. Patent Publication No. 2005/0163435 to Fincato discloses an optoelectronic device on a support substrate, and an optical component integrated within the substrate for coupling the optoelectronic device to an optical fiber. Some approaches, such as U.S. Patent Publication No. 2005/0163435 to Fincato, may include, in addition to what is discussed above, high manufacturing difficulties and reduced efficiency.